Extend the `amendOperation` mechanism for translating dialect attributes
attached to operations from another dialect when translating MLIR to
LLVM IR. Previously, this mechanism would have no knowledge of the LLVM
IR instructions created for the given operation, making it impossible
for it to perform local modifications such as attaching operation-level
metadata. Collect instructions inserted by the LLVM IR builder and pass
them to `amendOperation`.
This patch moves the call for translating an MLIR module to LLVM IR to the
beginning of the translation process. This enables the use of dialect
attributes attached to `builtin.module` operations and the `amendOperation()`
flow to initialize dialect-specific global configuration before translating
the contents of the module.
Currently, this patch does not impact the generated IR on its own. Testing
infrastructure to allow translating the Test dialect to LLVM IR is added, so
that it can be checked that the current behavior is not broken in the future.
Differential Revision: https://reviews.llvm.org/D158278
